The invention relates generally to a cooling system for electronic devices, and in particular to processes for fabricating microchannels for circulating a fluid in a device cooling system.
The development of high density power electronics has made it increasingly more difficult to fabricate efficient cooling systems. With modern silicon based power devices capable of dissipating heat up to 500 W/cm2, there is a need for improved thermal management solutions. Natural and forced-air cooling schemes can only handle heat fluxes of up to about 1 W/cm2. Conventional liquid cooling plates can achieve heat fluxes of the order of 20 W/cm2. However, microchannel cooling technology has demonstrated the ability to greatly enhance cooling performance, on the order of about 1000 W/cm2.
In certain proposed structures, microchannels are fabricated on the reverse side of power devices through which a coolant fluid is circulated to dissipate heat generated by the device. The efficiency of cooling depends on the width and the uniformity of the channels. Within certain limits, for example, narrower channels tend to dissipate heat better due to better contact with the coolant fluid. However, the increased heat transfer in narrower channels may often be offset by increased pressure losses across the channel, which may result in challenges in forcing cooling fluid through the system. Another limitation may be the non-uniformity of the microchannels, which may result in hot spots that may adversely affect the performance of the power device and may even result in break-down of the devices. Silicon is the commonly used material for microchannel fabrication. However, channels made of material having higher thermal conductivity than silicon may show better efficiency due to their better heat transfer properties.
Moreover, while such structures have been proposed and tested, efficient and economical method for their manufacture is still lacking. The stringent requirements of reliably creating uniform microchannels have simply not been addressed adequately in the art.
Therefore, there is a need for improving the current techniques for fabricating microchannels with narrower channel width and better uniformity. There is, in particular, a need for fabricating such devices in an efficient, low-cost manner.